An organic light emitting display device is a self-emission display device which has an organic light emitting diode which emits light to display an image. Since the organic light emitting display device does not require a separate light source unlike a liquid crystal display, it is possible to relatively reduce thickness and weight thereof. Further, since the organic light emitting display device has characteristics such as low power consumption, high luminance, and high response speed, the organic light emitting display device receives attention as a display device for portable apparatuses.
In general, organic light emitting display devices include a hole injection electrode, an organic emission layer, and an electron injection electrode. In the organic light emitting display device, a hole supplied from the hole injection electrode and an electron supplied from the electron injection electrode are coupled with each other in the organic emission layer to form an exciton, and light is generated when the exiton falls in a ground state.
However, in many organic light emitting display devices, external light emitting efficiency is not high. Particularly, the organic light emitting display device has a multilayer laminated structure in which a plurality of layers is laminated, and the light generated from the emission layer needs to pass through the multilayer laminated structure in order to display the light outside. While the light passes through the multilayer laminated structure, the light generated from the emission layer is lost in the device due to total reflection and the like and as a result, a ratio of which the light is not displayed outside is high. Accordingly, in the organic light emitting display device, by reducing an amount of light lost in the inside, it is required to increase a ratio of light displayed outside and increase overall light emitting efficiency.